It's Looking Like FSGSBASE Support Might Finally Land In Linux 5.9

Written by Michael Larabel in Intel on 19 June 2020 at 12:09 AM EDT. 11 Comments
It's looking like the Linux kernel support for the FSGSBASE instruction that has been present since Intel "Ivy Bridge" CPUs might finally see mainlining with Linux 5.9.

FSGSBASE is the instruction that can help with the performance of some workloads. FSGSBASE can help a variety of workloads including context switch heavy workloads and software like Java. In our past testing of the FSGSBASE patches we found it helped performance by ~3%.

Intel engineers previously worked on the patches that have been available in various forms for years. It was more recently though that Microsoft began pursuing these Linux patches for helping performance that they found did help some of their internal workloads.

After going through thirteen rounds of review, the FSGSBASE patches are now living at tip.git's x86/fsgsbase branch that was newly created by Thomas Gleixner. He announced the move of these patches into his Git tree, which is then one step away from being mainlined. Assuming everything continues to pan out fine in testing, the FSGSBASE patches could be sent in by Gleixner as part of the x86 changes for the Linux 5.9 cycle that will kick off later this summer.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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